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Feb-27-11
 | | David2009: G Grigore vs Holzke, 1993 White 25? Insane White has temporarily RRP for Q but is in dangter of losing material: how best to save it?
25.Bd5 drops the exchange. Instead 25.b4!? might work hoping for 25...Qxb4?! 26 Rxd4 exd4?! 27 Bd6+ Qxd6 28 Nxd6 Kxd6 29 Bxb5 a safe exchange ahead.
Instead 26...bxc4 27 Rdxc4 and White is consolidating- the Nf7 can escape via g5.
Black has 25...Qb6 and White has to surrender material with 26 Bd5 Ne2+ 27 Kf1 Nxc1 28 Nxc1, but Black's Queen is slightly less active and White recirculates his Bh2 with Bg1 then f3. To win,
Black has to creae a passed Pawn somewhere: not easy. Black has other moves, too much to analyse.
Time to check:
===
Missed it.
click for larger view
I had seen but dismissed 25 Rxd4 exd4 26 Bd6+ because of Kf6, not seeing the force of e5+. Instead, 25 b4? fails to 25...Qa3! which seems to win material. Crafty End Game Trainer check of the puzzle position as above.
http://www.chessvideos.tv/endgame-t...
You are white, drag and drop the move you want to make . Enjoy finding the win. The EGT improves on the game defence, so be careful! Postscript: Characteristically interesting analysis from <Phony Benoni> and <Jimfromprovidence: [snip] At first I thought 25 b4, but this is no good because black has 25...Qa3, attacking the c rook and pinning the d rook.> Congratulations on finding this! <I also liked 25 Rxd4 exd4, but I preferred 26 Bd5 next.> Against 26.Bd5 the EGT defends with 26...Nf6 and if 27.Bd6+ Kd7 28.Rc7+ Qxc7 29.Bxc7 Kxc7 to leave 
click for larger view
a difficult ending (White to play). Supplementary EGT link:
http://www.chessvideos.tv/endgame-t... Postscript part 2: <patzer2>'s analysis will defeat the EGT in the original link (give or take a transposition) but beware of a wrinkle at the very end. If you want more than Q for R+B you need to snuff out a perpetual check possibility for Black. |
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Feb-27-11
 | | morfishine: <Once> Fascinating take on Star Wars II...as usual per your standards, a very entertaining and absorbing post (along with the first) |
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| Feb-27-11 | | dufferps: I thought black could have done well by offering up a Queen sacrifice (30. ... Qc1+, 31.Rxc1 Bxd6 ....) and the white's threat is in shambles. White then has a material advantage (a rook and a pawn), but must capitalize on it. He must protect his exposed pieces, then work on a new attack. When I first looked at this situation, I thought white must draw back the bishop and knight before anything else.
However, it turns out that if white follows with Rd1 (essentially killing white's advanced, but isolated, d-pawn), his other pieces all have a tempo to withdraw safely and effectively, and white still wins rather easily. |
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Feb-27-11
 | | Patriot: I had a lot of difficulty with this one. First off I slightly miscounted the material: 2 rooks + bishop pair for a queen (white has an additional pawn). I thought white may be able to just play 25.Bd5 and be slightly ahead. That's ok to keep in mind, but more forcing ideas should be considered. The only two that came to mind were capturing on e5 (with bishop or knight) and removing the guard on the d4-knight or Rxd4 with the idea of Bd6+ next. I feel that I flip-flopped between the two ideas too much because there seemed to be nothing concrete. But the fact is that capturing on e5 is more dangerous simply because the bishop is still hanging on c4. In the end, black seemed to be better. But I finally decided on 25.Rxd4 because it was interesting, not because I saw it to the end. I saw the correct sequence but just couldn't find a key move. 25.Rxd4 exd4 26.Bd6+ Ke8 27.Be6 (threatening mate). I thought "What happens after 27...Qa6?" and didn't see that 28.Rc7 refutes it. Since 27...Qa6 seemed to refute my idea, I didn't bother looking for anything else that might refute it (like 27...Nb6). Also at the beginning I wondered how it might go if black decides 25...bxc4, but didn't look at this too much since white could move the rook which amounts more or less a trade where white loses the bishop pair. Another possible refute in the game line was 26.Bd6+ Kf6, but white seemed to have good attacking chances starting with 27.e5+ Nxe5 28.Bxe5+ so I thought 26...Ke8 might be a stronger defense. So my answer was 25.Rxd4 with unclear results. |
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| Feb-27-11 | | alachabre: Black's King is dangerously exposed. The knight on d4 is well posted, and I would like to get rid of it, so a typical exchange sacrifice is to be considered as my first candidate move. 25. Rxd4 exd4
This has the nice side-effect of clearing the h2-b8 diagonal, so why not 26. Bd6+ Kf6
27. g4 bxc4
I guess that's out.
27. e5+ Kf5
28. g4+ Ng5+
29. Kf5 Ne6+
30. Ke4
And I'm stuck. I know the King is in big trouble, but I don't see the crusher. Taking a look at the other way out for Black: 26. ... Ke8
27. Be6 Qa6
28. Rc7
This looks pretty overwhelming. What's better than Qa6? 27. ... Nb6
I don't like this for Black, as it seals off the queen from the defense. 28. Rc7 Bf8
29. Bxf8
and with the queen out of action (Qe1+ Kh2 leads nowhere, seems like), White should be able to press the attack to advantage from here. So, not an exhaustive analysis, but instinct and tracking a couple of quick lines shows the rook sac to be sound. Oh wait, I forgot this significant variation: 25. Rxd4 bxc4
This has to be looked at.
26. Rdxc4 and retains a solid material and positional advantage. Oops, no, the knight is hanging. 26. Rd5 Qxa2
27. Nxe5
A complicated position, but it appears White keeps the upper hand. |
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| Feb-27-11 | | charms: What I find most amazing that White either was lucky or he saw the whole sequence as early as move 20. From then on, everything is forced, and White somehow emerges on top as the smoke disperses. |
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Feb-27-11
 | | Jimfromprovidence: <David2009> Thanks for picking up my thread after the line 25 Rxd4 exd4 26 Bd5. <Against 26.Bd5 the EGT defends with 26...Nf6> The position after 26...Nf6 I could not crack, So I had to use Rybka freeware. It finds the great resource 27 Bc7!, threatening 28 Bb6+. 
click for larger viewThe importance of this set up move is that it makes the queen give up control of the a5-d8 diagonal, forcing the queen to a6. Now, after 28 Bb6+, black's king cannot move to d7 because of the threat Rc7+. So after 27...Qa6 28 Bb6+ black has to play 28...Ke8. 
click for larger viewNow white can win after 29 Rc6 Qb7 30 Be5, threatening both 31 Nd6+ and 31 Re6+.
click for larger view |
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Feb-27-11
 | | agb2002: From an Open Game or Indian Defense, I can't figure it out. White has two rooks, the bishop pair and a pawn for a queen, a bishop and a knight. Black threatens 25... bxc4. If 25.Bd5 then 25... Ne2+ wins the exchange. The knight on d4 is so well placed that one is tempted to apply the "Shoot first, ask later" method. Then, pulling the threads, 25.Rxd5: A) 25... exd4 26.Bd6+
A.1) 26... Ke8 27.Be6 (trying 28.Rc8#)
A.1.a) 27... Nb6 28.Rc7 Qe1+ 29.Kh2 Bf8 (to avoid Re7+ and the windmill) 30.Bxf8 Kxf8 31.Nd6 d3 (31... Qxf2 32.Rf7+ Qxf7 33.Bxf7 Kxf7 34.Nxb5 + - [2P]) 32.Rf7+ Kg8 33.Ne8 with the double threat 34.Rf3+ Kh8 35.Rf8# and 34.Nf6+ Kh8 35.Rxh7#. A.1.b) 27... Qa6 28.Rc7 Nf6 29.Re7+ Kf8 30.Rxa7+ wins the queen. A.2) 26... Kf6 27.e5+
A.2.a) 27... Kf5 28.g4+ Ke4 (28... Kf4 29.e6+ Ne5 30.e7 + -) 29.b4 Qa6 30.Re1+ Kf3 31.Bd5+ Kf4 32.e6+ Ne5 33.e7 + -. A.2.b) 27... Nxe5 28.Bxe5+ Ke7 29.Bb3 Bxe5 30.Nxe5 + - [R+B+N+P vs Q]. B) 25... bxc4 26.Rd5 Qxa2 27.Nxe5 Nxe5 28.Bxe5 Bxe5 29.Rxe5+ and the rooks will capture the black pawns on the queen side with a won endgame. |
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| Feb-27-11 | | LIFE Master AJ: I looked at this one for about 10 minutes.
If I had to guess, I would say 25.Rxd4. (sack)
Actually, White does not stand that badly, I thnik he has two Rooks for the Queen. (Not as crazy as some Sundays.) 12:13 PM Sunday / Pensacola time. |
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| Feb-27-11 | | castle dweller: I got the first few moves but couldn't quite put it together and rescue my advanced troopers in the end - " A check too far" for me. |
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| Feb-27-11 | | gofer: Well, I can see a very nice combination that black has to avoid, so black cannot
accept the sacrifice, so we probably follow this line, which looks to be winning
for white...
<25 Rxd4 bxc4>
<26 Rd5 Qxa2?>
<27 Nxe5 Nxe5> (... Nb6/Nf6 28 Nc6+ seems to be good for white)
<28 Bxe5 Bxe5>
<29 Rxe5+ Kd6>
<30 Rd5+ Kc6>
<31 Rd4 winning>
But lets look at the acceptance, which is much more interesting! <25 Rxd4 exd4>
<26 Bd6+ ... >
Black has two choices Ke8 and Kf6. Kf6 loses quite quickly! 26 ... Kf6
27 b4 Qa6 (Qa3 28 Rc6! and 29 Bf8# next)
28 Rc6 Qxc6
29 Bxc6 Kxf7
30 Bxd7 winning
<26 ... Ke8 >
<27 Bd4! ...>
click for larger viewWhite is threatening Rc8#. Bf6 moves and Qd8 moves lose the queen, so Nb8/Nb6/Nf8/Nf6 are the only ones available! 27 ... Nf6 28 Nd5! winning
27 ... Nb8 28 Be6! winning
27 ... Nf8 28 Rc7 Bf6 29 Bd5! winning
<27 ... Nb6>
<28 b4 ...>
I have looked at the variations after this and cannot find a way forward for white... ...pity! Time to check what I
have missed! |
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| Feb-27-11 | | kutuzov: Got the jist of this one.
I saw Rxd4, the bishop check afterwards, that Kf6 was swiftly met with e5+, and that capturing the bishop led to Rd5 followed by doubling the rooks. Didn't even bother to look at Ke8. It seemed like a losing move, but there is a little more nuance than I thought. 28. b4 is the key to the whole combination, preventing the back rank mate and allowing the rook complete the mating net on c7. Even though I dismissed the main line a little bit, I'll still give myself a pat on the back. :) |
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| Feb-27-11 | | alachabre: <kutuzov>, I have to disagree, I think 28. b4 is irrelevant, although it did induce Black to blunder Qa3. There is no back rank mate, h2 is open. |
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| Feb-27-11 | | Rama: Scormus, refer to Averbakh's "Advanced Chess Tactics" where he elucidates the Theory of Contacts. Each contact is a potential capture. As the number of contacts grows so does the potential for a combination. I learned a lot from that book. |
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| Feb-27-11 | | alachabre: <scormus>, re your comment about never playing an exchange sacrifice OTB, reconsider! If the position calls for it, it is one of the strongest tactics available to the player. Now, I may have a bias for liking it; you see, my only victory over a master in a rated game featured an exchange sac very much like the one in this game. I seek them out now, if it's even just a little bit sound, it can have great shock value. |
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| Feb-27-11 | | checkmateyourmove: great puzzle, worthy of a sunday! |
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Feb-27-11
 | | scormus: <alachabre and Rama> thanks, and youre right about the tactical strengh of such a sac. I suppose what I mean is ... its one thing to find it in a puzzle and post it on the forum, another to play it in a match when your team needs you to not lose. I admit, there've been games I didnt win because I chickened out of playing the important sac. I suppose whats really important is knowing to play a winning sac even if you cannot see the sequence right through. A very strong club mate once pointed this out after a game, saying "I might not be able to see the whole sequence but I know it wins. How? These positions always do." I hope I these puzzles are helping me to learn this. |
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| Feb-27-11 | | JKnight94: @ alachabre "I have to disagree, I think 28. b4 is irrelevant, although it did induce Black to blunder Qa3. There is no back rank mate, h2 is open." In fact b4 is necessary. If white plays 28. Rc7 immediately black follows up by 28...Qe1+ 29. Kh2 and Bf8! Note that white can't play Ng5 now because Bxd6+ is check. When white played 28. b4 he actually stopped the queen from being able to enter the first rank, stopping the king from coming to h2 and therefore having the option to play Ng5 later which is crushing. So it was relevant after all wasn't it? |
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| Feb-27-11 | | theodor: I checked out for 25. ..;bxB , but didnt found any! |
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| Feb-27-11 | | AGOJ: Well, I have to say I missed it because after 25.Rd4 bxc4 I couldn't see a clearcut continuation for White. Taking the rook with 25...exd4 seemed to me a mistake, and inferior to 25...bxc4. Perhaps someone with access to computer analysis can enlighten me. |
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| Feb-27-11 | | alachabre: <JKnight94>, I appreciate the analysis, but I still disagree. I see that b4 does help deflect the queen from the first rank, but only if Qa3 is played. If Qa4, there is no real difference from an immediate 28. Rc7 - the Black queen can still safely gain the first rank. After your 29. ... Bf8, 30. Bxf8 is solidly winning for White. |
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| Feb-27-11 | | Combopack: Can someone explain the 23. Nd7 move by black. Why not Kxd8? |
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| Feb-27-11 | | stst: late in the game...
25. Rxd4 exd4
26. Bd6+ Kf6
(the other option is Ke8, also won by W.)
27. b4 Qa6 / Qa3 (doesn't matter much.)
28. Bd5 d3
29. e5+ Nxe5
30. f4 d2
31. fxe5+ Kf5
32. Rf1#
somewhat messy (quite a lot of sub-variations,) not too insane!!
Now is bed time!! |
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Feb-27-11
 | | Phony Benoni: <Combopack: Can someone explain the 23. Nd7 move by black. Why not Kxd8?> 
click for larger viewLooks like our old friend <24.b4> comes into play here. If Black tries to defend the e-pawn with 24...Qxc7, then 25.Rxd4+ since the e-pawn is pinned. On other queen moves, White plays 25.Bxe5, regaining the piece with all his forces centralized and aiming at the Black king. I suspect Black knew by now that this wasn't going to be all fun and games. |
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Feb-27-11
 | | sevenseaman: < Combopack: Can someone explain the 23. Nd7 move by black. Why not Kxd8?> 23... Kxd8 24. b4 Qxb4 25. Bxe5 only serves to make White's job easier. |
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sac: 25.Rxd4
